Major code rework to straighten up the logic considerably. This should
fix another issue raised with milestone displayed at wrong day.
Thanks to Ryan J. Ollos for pre-release testing this non-trivial subject.

We perpare to develop for Trac 0.12 exclusively. While 0.11 will still be
maintained for a while, there is no need for 0.11dev anymore.
Furthermore we'll start backporting important things from trunk instead.